Abstract:

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We have used depth-resolved cathodoluminescence and Auger electron spectroscopies,
DRCLS and AES, respectively, to probe the electronic structure and the composition of Ti/Al
ohmic contacts to p-type SiC on a nanometer scale. A continuous Ti-Si-C compound layer was
observed using the Auger depth profile. No interfacial Al segregation was found. The secondary
electron threshold technique showed a continuous decrease in work function from the p-type SiC to
the Ti-Si-C compound layer. Our results support an ohmic contact mechanism by an intermediate
semiconductor layer which reduces the otherwise large interfacial Schottky barrier height. DRCLS
revealed a ~2.78 eV sub-band gap transition enhanced by interfacial reaction in the near-interface
SiC, suggesting the formation of additional C or Si vacancies.

Abstract: The effects of argon and nitrogen bombardment of 3C-SiC surfaces at acceleration voltages
below 2 keV were studied by stylus profilometry, reflectometry, reflection high energy electron
diffraction and Auger electron spectroscopy (AES). The erosion rate of the SiC surface was
determined. It was found that the sputtering rate for argon was three times higher compared to nitrogen.
AES measurements revealed argon and nitrogen incorporation at a depth of a few nanometers
as well as stoichiometric changes at the same depth scale independent of the acceleration voltage.
In the case of the interaction of nitrogen ions with the 3C-SiC surface the formation of a SiCNalloy
was detected.

Abstract: Silicide sequential phase formation during tens-of-nanometer-thick metallic film reaction on Si substrate has been extensively studied. Nevertheless, the reasons of sequential phase formation are still under debate, and have been poorly studied at the atomic scale. Using atomistic kinetic Monte Carlo simulations, we show that considering a binary fcc non-regular solid solution, without diffusion asymmetries, the diffusive reaction of a sub-nanometer-thick film (~5 atomic monolayers) on a semi-infinite substrate leads to the sequential formation of all the phases present in the binary phase diagram, starting with the film atom richest phase. These predictions are supported by experimental observations: the dissolution of a 4 monolayer-thick Si film on a Ni(111) substrate, during in-situ ultra high vacuum Auger electron spectroscopy, shows delays and kinetic changes in the dissolution process that may correspond to the sequential formation of the Ni-Si compounds, i.e. NiSi2, NiSi, Ni3Si2, Ni2Si, Ni31Si12 and Ni3Si.

Abstract: Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) studied the interaction of argon ions with a natural oxide layer of polycrystalline aluminum. It was found that the bombardment of argon ions with an energy lower sputtering threshold Al2O3 leads to accumulation of ions bombarding the interstitial voids in the surface, thereby forming a solid solution of atoms of the target, the argon ions and nitrogen ion beam, the captured residual gas from the chamber of the spectrometer.

Abstract: Silicide growth via reaction between a metallic film and a Si substrate has been well documented. In general, atomic transport kinetic during the growth of silicides is considered to be the same as during equilibrium diffusion, despite the reaction and its possible injection of point-defects in the two phases on each side of the interface. To date, the main studies aiming to investigate atomic transport during silicide growth used immobile markers in order to determine which element diffuses the fastest during growth and in which proportion. The quantitative measurements of effective diffusion coefficients during growth was also performed using Deal-and-Groove-type of models, however, these effective coefficients are in general not in agreement with the interdiffusion coefficients calculated using the equilibrium diffusion coefficients measured during diffusion experiments. In general, atomic transport kinetic measurements during growth and without growth are performed using different types of samples for experimental reasons. In this paper, we discuss the possible use of ultrahigh vacuum in situ Auger electron spectroscopy in order to measure the effective diffusion coefficient during growth, as well as the equilibrium self-diffusion coefficients, in the same samples, in the same experimental conditions. The first results on the Pd-Si system show that atomic transport during Pd2Si growth is several orders of magnitude faster than at equilibrium without interfacial reaction.